Gridded MOS GRIB2 Encoding Details

The GFS-based Gridded MOS guidance is provided on the 2.5 km CONUS NDFD (experimentally), 5km CONUS NDFD, 3km Alaska NDFD, and 2.5km Hawaii NDGD grids in GRIB2 format. The products are disseminated via two mechanisms. GRIB2 files are currently available on the NWS FTP server. Descriptions of the file locations and names are available. The files on the ftp server contain multiple grids in each file, grouped by element. The gridded MOS products are also officially disseminated via the NWS Satellite Broadcast Network (SBN) and NOAAPORT. The guidance is sent with each grid as a separate product with its own unique WMO header. See the list below for links to WMO headers for each domain.

This webpage seeks to provide users with some of the settings we are using to encode our products in GRIB2. Users should consult the WMO's GRIB2 handbook for the complete details on GRIB2 encoding.

Section 0 - Indicator Section

For all Gridded MOS GRIB2 prodcuts we set octet 7, Discipline, to 0 for Meteorological. We use GRIB edition 2 in octet 8.

Section 1 - Identification Section

Select Octet No.

Value

Explanation

6-7

7

Originating Center - NCEP

8-9

14

Originating Sub-center - MDL

10

1

initial operational version number

11

0

Version of local tables

12

1

Significance of date in Octets 13-19

13-19

Year, Month, Day, Hr, Min, Sec

Date of model run on which guidance is based

20

0

Operational products

21

1

Forecast products

Section 2 - Local Use Section

For the Gridded MOS element weather, MDL GRIB2 encoding software uses the Local Use section for packing metadata unique to each grid. At this time, for parameters other than weather, t
he Local Use section is omitted. For more information on weather and MDL use of the Local Use section, click here.

Section 3 - Grid Definition Section

The Gridded MOS guidance is presented on the 2.5-km NDFD grid and 5-km NDFD grid for the CONUS; 3-km NDFD grid for Alaska; and 2.5-km NDFD grid for Hawaii. The following are the grid specifications used to pack the guidance into GRIB2.

Section 4 - Product Definition Section

The Gridded MOS products are packed using either Product Definition Template (PDT) 4.0, 4.8, or 4.9. The following tables list
the settings for each element.

Guidance Valid at a Point in Time - PDT 4.0

Octet No.

2-M Temperature (K)

2-M Dewpoint (K)

Relative Humidity (%)

Wind Speed (m/s)

Wind Direction (degrees)

Wind Gusts (m/s)

Opaque Sky Cover (%)

Weather

1-4

Length of section in octets

5

4

6-7

0

8-9

0

10

0

0

1

2

2

2

6

1

11

0

6

1

1

0

22

1

226

12

2

13

missing

14

96

15-16

missing

17

missing

18

1

19-22

hours from reference time to valid time (i.e. projection)

23

103

103

103

103

103

103

1

1

24

0

25-28

2

2

2

10

10

10

0

0

29

missing

30

0

31-34

0

Guidance Valid Over a Period of Time - PDT 4.8 (see below for POPs)

Octet No.

Maximum Temperature (K)

Minimum Temperature (K)

Snowfall Amt (m)

3-hr tstm (%)

6-hr tstm (%)

12-hr tstm (%)

6-hr Precip Amount (kg/m*2)

12-hr Precip Amount (kg/m*2)

1-4

Length of section in octets

5

4

6-7

0

8-9

8

10

0

0

1

19

19

19

1

1

11

4

5

29

2

2

2

8

8

12

2

2

2

5

5

5

2

2

13

missing

14

96

15-16

missing

17

missing

18

1

19-22

hours from reference time to beginning of forecast period

23

103

103

1

1

1

1

1

1

24

0

25-28

2

2

0

0

0

0

0

0

29

missing

30

0

31-34

0

35-36

Year of end of forecast period

37

Month of end of forecast period

38

Day of end of forecast period

39

Hour of end of forecast period

40

Minute of end of forecast period

41

Second of end of forecast period

42

0 (1 for Hawaii GMOS). Future updates to GMOS will change this value to 1 also.

1

43-46

0

47

missing

1

missing

1

48

missing

49

missing

1

50-53

missing

24

3

6

12

6

12

54

missing

55-58

missing

Guidance Valid Over a Period of Time - PDT 4.9 -- POPs

Octet No.

6-hr POP (%)

12-hr POP (%)

1-4

Length of section in octets

5

4

6-7

0

8-9

9

10

1

11

8

12

2

13

missing

14

96

15-16

missing

17

missing

18

1

19-22

hours from reference time to beginning of forecast period

23

1

24

0

25-28

0

29

missing

30

0

31-34

0

35

missing

36

missing

37

1

38

missing

39-42

missing

43

3

44-47

254

48-49

Year of end of forecast period

50

Month of end of forecast period

51

Day of end of forecast period

52

Hour of end of forecast period

53

Minute of end of forecast period

54

Second of end of forecast period

55

1

56-59

0

60

1

61

missing

62

1

63-66

6

12

67

1

68

0

Section 5 - Data Representation Section

We use Data Representation Template 5.3: Gridpoint data - complex packing and spatial differencing. All fields are packed as floating point values except for wind direction which is packed as an integer.

For scaling, we use the following decimal scaling factors:

Temperatures

Wind Speed/Gusts

Wind Direction

Percentages (POP, RH and Opaque Sky)

Precipitation Amt

Snowfall Amt

Weather

1

1

0

0

3

5

0

Binary scaling will be used only for the 2.5 km CONUS grids. Learn more about binary scaling here. The following binary scaling factors will be used.